1. Technical Field
This disclosure relates to content insertion into digital media streams. In particular, this disclosure relates to providing frame accurate content insertion triggers in digital video streams communicated to downstream endpoints.
2. Related Art
Content providers have long faced the problem that their global programming often includes commercial content not relevant to destination markets. Consider, for example, live broadcast video of a ping pong tournament from South Korea. The original broadcast would typically include commercials in the Korean language and specific to Korean products and services. Although suitable for the primary market in South Korea, those commercials are of little or no value for a secondary market, for example the United States or Brazil. In an age of worldwide satellite and cable distribution of programming, there are enormous possibilities for reaching additional markets, but corresponding challenges in localization.
For this reason, broadcast networks have evolved to include mechanisms for local commercial replacement. The replacement is highly accurate and reliable. In particular, the replacement happens on a “frame accurate” basis, which means that local content providers can insert a replacement commercial starting at any desired frame within the video stream. One way in which frame accurate replacement has been done is to insert special dual tone multifrequency (DTMF) tones in the live content stream (e.g., in a subband in the accompanying audio). Local content providers have the benefit of accurate timecode that accompanies the broadcast, and are able to find the DTMF tones and interpret them as content insertion triggers. Because the timing of playout of content is known down to the frame level, the local content providers can replace commercial content with locally relevant commercials without any degradation to the original broadcast, and do so consistently across all of their subscribers.
At the same time, explosive growth and development in high speed digital communication technologies, coupled with highly efficient encoding, today makes virtually any content available anywhere in the world, given a suitable Internet connection. Timecode, however, is not generally available in digitally encoded video. Instead, digital communication of broadcast video relies on transcoding a linear baseband stream of video and audio into a highly compressed linear stream carried in Internet Protocol (IP) packets. The transcoding process typically introduces a delay because of the processing time necessary to generate the compressed linear stream. The delay varies unpredictably depending on the encoding complexity of each frame of video. Because of the unpredictable delay, IP encoded streams cannot be delivered frame accurately. As a result, local content providers could at best only guess at where in the received digital video stream to insert local replacement commercials. In other words, the local content providers were unable to match, on a frame accurate basis, the replacement triggers specified in the original broadcast video.
A need has long existed to address the problems noted above and others previously experienced.